The Drake SC-2 is a 2 meter receive converter. Its potential receive range is 144-148 MHz. With the 25.1 MHz crystal that is supplied with the Drake R-4A, it will receive 144-144.5 and 145-145.5 MHz. If a 25.6 MHz crystal is added the to the R-4A, then coverage is 144-146 MHz. Further, if auxiliary crystals 27.1 and 27.6 MHz are also added, then the entire 2 meter band will be covered.